U.S. patent number 5,376,057 [Application Number 08/087,222] was granted by the patent office on 1994-12-27 for multistage differential gear package.
This patent grant is currently assigned to Ingersoll-Rand Company. Invention is credited to Timothy R. Cooper, Scott A. Delozier.
United States Patent |
5,376,057 |
Cooper , et al. |
December 27, 1994 |
Multistage differential gear package
Abstract
A gear set is provided having a plurality of two-stage
intermediate gears which do not require indexing on assembly or
reassembly of the gear train. This is provided by aligning the
two-stage gear teeth in axial alignment tooth for tooth between the
stage while maintaining an appropriate number of teeth on the input
and output gears.
Inventors: |
Cooper; Timothy R. (Owego,
NY), Delozier; Scott A. (Milan, PA) |
Assignee: |
Ingersoll-Rand Company
(Woodcliff Lake, NJ)
|
Family
ID: |
22203845 |
Appl.
No.: |
08/087,222 |
Filed: |
July 8, 1993 |
Current U.S.
Class: |
475/248; 475/339;
475/340; 74/413; 74/414; 74/421R |
Current CPC
Class: |
F16H
1/22 (20130101); F16H 1/227 (20130101); Y10T
74/19679 (20150115); Y10T 74/19651 (20150115); Y10T
74/19647 (20150115) |
Current International
Class: |
F16H
1/22 (20060101); F16H 1/02 (20060101); F16H
001/04 () |
Field of
Search: |
;74/412R,413,414,421R,462 ;475/248,331,338,339,340,344 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Marmor; Charles A.
Assistant Examiner: Kwon; Peter
Attorney, Agent or Firm: Vliet; Walter C.
Claims
What is claimed is:
1. A universally aligned multistage differential gear package
comprising:
a gear frame operatively connected to a set of two stage gears;
an input gear for driving said set of two stage gears;
an output gear being driven by said set of two stage gears; and
wherein the number of teeth on said input gear and said output gear
are integer multiples of the number of said two stage gears, and
wherein the number of teeth on the first stage of said two stage
gears is equal to the number of teeth on the second stage of said
two stage gear, and all teeth on said second stage of said two
stage gear are fabricated in axial alignment with said teeth on
said first stage of said two stage gears.
2. A universally aligned multistage gear package according to claim
1, wherein all of the intermeshing gears are spur gears.
3. A universally aligned multistage differential gear package
according to claim 1, wherein the input gear is in the form of an
internal ring gear.
4. A multistage differential gear package according to claim 1,
wherein said output gear is in the form of a ring gear.
5. A multistage differential gear package according to claim 1,
wherein both said input gear and said output gear are in the form
of a ring gear and said two stage gears are in the form of spur
gears.
6. A multistage differential gear package according to claim 1,
wherein a pair of two stage gears are provided.
7. A multistage differential gear package according to claim 1,
wherein a plurality of two stage gears are provided.
8. A multistage differential gear package according to claim 1,
wherein said two stage gears are mounted for rotation in said fixed
gear frame.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to reduction gear packages and
more particularly to a universally aligned multistage differential
gear package for use with power tools and the like wherein assembly
may be accomplished without regard for specific gear alignment or
indexing during assembly. Typically, multistage differential gear
units using a plurality of intermediate two stage gears have
required specific indexing on assembly to assure proper gear timing
to prevent lockup and to permit the rotation of the gear package in
operation.
The foregoing illustrates limitations known to exist in present
devices and methods. Thus, it is apparent that it would be
advantageous to provide an alternative directed to overcoming one
or more of the limitations set forth above. Accordingly, a suitable
alternative is provided including features more fully discussed
hereinafter.
SUMMARY OF THE INVENTION
In one aspect of the present invention this is accomplished by
providing a universally aligned multistage differential gear
package including a gear frame operatively connected to a set of
two-stage gears; an input gear for driving the set of two-stage
gears; an output gear being driven by the set of two-stage gears;
and wherein the number of teeth on the input gear and the output
gear are integer multiples of the number of said two-stage gears,
and wherein the number of teeth on the first stage of the two-stage
gears is equal to the number of teeth on the second stage of the
two-stage gears, and all teeth on the second stage of the two-stage
gears are fabricated in axial alignment with the teeth on the first
stage of the two-stage gears.
The foregoing and other aspects will become apparent from the
following detailed description of the invention when considered in
conjunction with the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross section of a gear reduction set for a power tool
according to the present invention;
FIG. 2 is an end view of a two-stage gear according to the present
invention having a one to one ratio of the number of teeth in the
first stage to the number of teeth in the second stage;
FIG. 3 is a cross sectional view of the two-stage gear shown in
FIG. 2 taken at Section 3--3 of FIG. 2;
FIG. 4 is an isometric view of a two-stage gear according to the
present invention;
FIG. 5 is a schematic view of one embodiment of the present
invention utilizing spur gears for all gearing;
FIG. 6 is a schematic view of one embodiment of the present
invention utilizing spur gears for the input gear and two stage
gears and a ring gear for the output gear; and
FIG. 7 is a schematic view of one embodiment of the present
invention utilizing ring gears for the input and output gears and
spur gears for the two-stage gear.
FIG. 8 is a cross section view of a gear reduction set for a pair
of two stage gears.
FIG. 9 is a front end view of a gear reduction set for a plurality
of two stage gears.
DETAILED DESCRIPTION
Referring to FIG. 1, a power tool having a differential gear
reducer according to the present invention is generally shown by
reference numeral 1. The gear reducer is generally shown enclosed
in a casing 21 which may be conveniently attached to a motor
housing (not shown) containing a motor (also not shown) having its
output on a spindle 2. The spindle 2 is further provided with an
input pinion gear 22 which drives two or more circumferentially
spaced two-stage gears 34 through a first stage pinion 3 which in
turn is attached to a second stage pinion 4. The second stage
pinion 4 in turn drives an output spindle 5. The output spindle 5
is mounted for rotation within the housing 1 by means of a pair of
ball bearings 9, 10. The spindle further has its output on, for
example, a square drive 11, which, for example, may be utilized to
mount a socket which in turn may engage a fastener or the like (not
shown).
Referring again to FIG. 3, the first stage gear 3 of each of the
two-stage gears 34 is provided with gear teeth 15 which engage the
teeth 22 of the pinion 2. The second stage gear 4 of each of the
two-stage gears 34 is provided with gear teeth 20 which in turn
engage the gear teeth 25 of the output spindle 5.
As shown in FIG. 1, the two-stage gears are mounted in a gear frame
6. According to the present invention, two or more sets of
two-stage gears are provided. For purposes of the preferred
embodiment herein described we have chosen to include 3 two stage
gears 34 which are mounted in the gear frame 6 by means of gear
pins 7 which are pressed into bearings 8 provided in the gear frame
6. Where 3 two-stage gear sets are provided, they are spaced
approximately 120 degrees apart to balance and distribute the load
and to share the drive forces conducted through the gear set.
The multiple two-stage gears substantially increase the amount of
power that may be transmitted by a given gear set. However, in the
case of the prior art, it was necessary to carefully align the
two-stage gear sets to an indexed starting point. This was
time-consuming in assembly and servicing of the gear sets and in
the event this was not accomplished damage to the gear set could
occur.
According to the present invention, a multistage differential gear
set may be provided which is free of the index requirement. This is
accomplished as follows:
The number of teeth on the pinion and output shafts are integer
multiples of the number of two-stage gears, i.e.,
wherein:
T.sub.p =Number of teeth on the pinion
T.sub.os =Number of teeth on the output shaft
N=Number of two-staged gears
I.sub.1 and I.sub.2 =Integers=1, 2, 3, etc.
In this case, I.sub.1 can=I.sub.2 but does not have to.
The number of two-staged gears determines their spacing about the
gear package centerline, i.e.,
wherein
J=Spacing of two-staged gears in degrees.
According to the present invention, the number of teeth on the
first stage must be equal to the number of teeth on the second
stage of the two stage gear 34. Variation of the diametral pitch at
either end of the two-stage gear is acceptable.
Referring to FIG. 2, according to the present invention all the
teeth on the second stage gears must be fabricated such that they
are in axial alignment (tooth on tooth) with teeth on the first
stage. By fabricating the two-staged gears such that their teeth
are in axial alignment, it is insured that proper gear mesh will
occur at both ends of the two-stage gear at every J spacing.
FIG. 5 shows a schematic gear reduction set wherein all of the
reduction gears are spur gears. The reference numerals referred to
previously described elements as shown and described in FIGS.
1-6.
FIG. 6 shows a variation of the preferred embodiment wherein the
output gear is in the form of a ring gear or internal gear.
In FIG. 7 another embodiment is shown wherein both the input gear
2' and the output gear 5' are internal gears or ring gears.
Having described a number of alternative embodiments, other
variations may occur to one skilled in the art.
* * * * *